1. Field of Invention
This invention relates to vision testing deaf or severely hearing-impaired individuals, specifically to the means by which the examiner communicates the necessary instructions to the hearing impaired individual during the course of the examination.
2. Description of Prior Art
The usual means of communicating to deaf and hearing-impaired individuals are through the printed word, sign language, finger spelling, lip reading, gestures or by touch. Except for touch, the hearing-impaired individual must be able to observe the one attempting the communication. Other means of non-verbal communication for the handicapped have been developed. U.S. Pat. No. 4,406,998 to Willough, Sep. 27, 1983 discloses a device which allows communication through lighted message blocks. Many devices have been developed which allow communication from a handicapped person to another, such as the apparatus disclosed in U.S. Pat. No. 3,651,512 to Summers, Mar. 21, 1972.
A vision examination consists of many parts. Typically, an eye examination will include the patient case history, visual acuity testing, various eye health tests, muscle balance tests, objective refraction and subjective refraction. Visual acuity testing is accomplished using various types of visual acuity test targets and displays. A test distance between the patient and the test targets is typically twenty feet. Visual acuity test targets are known as optotypes. One such optotype is disclosed in U.S. Pat. No. 4,968,131 to Lewis, Nov. 6, 1990. Historically these test targets were presented to the patient as a wall chart having the optotypes imprinted on it. Currently, the most common method of presenting the optotypes to the patient is through the use of a chart projector which projects the optotypes upon a reflective screen. To permit adequate visualization of the projected acuity chart, the room is generally made dark. Alternative methods of displaying visual acuity charts have been developed. One such device is a translucent panel with imprinted optotypes which is rear-illuminated as disclosed in U.S. Pat. No. 5,129,720 to Jovicevic, Jul. 14, 1992. Another method employs a computer to generate optotypes upon a video display unit as disclosed in U.S. Pat. No. 4,239,351 to Williams, et al, Dec. 16, 1980. Testing of visual acuity and the use of optotypes is integral to the vision examination and is measured repeatedly during the subjective testing phase of the examination.
For most of the examination, the examiner is face-to-face with the patient. The examiner may communicate to a hearing-impaired patient during the case history and eye health tests with relative ease. This can be accomplished through printed material, lip reading or, if the examiner is so skilled, sign language or finger spelling. Alternatively, the examiner may use a sign language interpreter who must also be within the patient's view. It is when a deaf patient is positioned behind a refractor that difficulty arises in performing the vision examination.
A refractor is an optical device containing many lenses through which the patient looks at a visual acuity display. A refractor is also known as a phoropter. The lenses of a refractor may be selected to be presented to the patient individually or in combination. Besides lenses for determining the patient's refractive state, there are various lenses and devices for measuring the patient's extra-ocular muscle balance. Also, wheels and mechanisms for moving the lenses. In order to contain all of the necessary lenses, refractors are not small. Newer types of automated refractors are even larger as they must contain added machinery and electrical components to automatically position the lens combinations in front of the patient. A refractor covers at least the upper half of a patient's face, and extends several inches to either side of the face. It is very difficult for a patient to look around or to the side of a refractor. Often, a patient's head movement is further restricted by a headrest on the examination chair. The refractor has a very restricted field of view through the lens apertures. Little else besides the acuity chart is visible to the patient. As the room is generally dark, this further impedes the patient's ability to visualize anything besides the acuity chart. Once positioned behind a refractor, the hearing-impaired patient has been effectively cut off from further visual communication from the examiner or the interpreter.
Typically, to perform a subjective refraction, the examiner presents to the patient various sets of lens combinations through the refractor. The patient is asked to choose which lens combination out of a set of choices gives the better focus. Using that information, the examiner presents another set of choices. Usually, the initial choices will show a distinct difference between them. As the examination progresses and the examiner is closer to determining the patient's glasses prescription, the difference between the choices becomes more subtle. Often, unless alerted through another clue, a patient may be unable to recognize that a different lens combination has been presented.
During this subjective refraction process, the examiner needs to find out how well the patient is seeing through a particular lens combination. The patient is asked to read the letters on the acuity chart. If the patient can read the letters of a particular size, the examination can then continue with letters of a smaller size. This process continues until the examiner is satisfied that no other lens combination will allow the patient to read smaller letters.
From this discussion, it is apparent that the examiner must communicate to the patient. The examiner must be able to indicate that the patient is about to be shown a set of lens choices. Then the examiner must be able to label each choice (e.g. choice one or choice two). This label must be able to be maintained through several presentations of the same set of choices to allow the patient a more thorough evaluation of each choice. The examiner needs to be able to indicate that a different set of choices is about to be presented to repeat the cycle. Finally, the examiner needs to be able to demand a response from the patient--either to make a choice of the presentations or to read aloud the letters presented.
Currently, there are not any satisfactory means for communicating with the hearing-impaired individual during a subjective refraction. Those methods now employed by vision examiners are as follows:
a) The examiner may position the patient behind the refractor, and by waving his or her hand in front of the fine of sight of the patient, attempt communication. This method is unsatisfactory for several reasons. The communication becomes ambiguous and confusing. The examiner may not flag the examinee in exactly the same way each time so the patient can easily become confused and unsure of the given signal. The examiner's hand may momentarily obscure the view of the visual acuity chart which also is distracting and confusing to the patient. Also, the patient may change focus from the acuity chart, which is set at a particular test distance, to the examiner's hand which would only be a very short distance in front of the patient. This change of focus with the need to then refocus to the distance of the acuity chart may cause inaccurate results in the measurement of the patient's refractive state. PA1 b) The examiner may not perform a subjective refraction at all. Instead, the examiner may only use the information from the objective refraction to prescribe the vision correction. Objective refraction is a method whereby the examiner uses various means to measure the patient's refractive state without feedback from the patient. Retinoscopy and automated refractors are examples of objective refraction. Even the most sophisticated objective refraction technique is not, at present, as accurate a method of determining a patient's refractive state as subjective refraction. In some instances, objective refraction is completely inaccurate and must be entirely disregarded, as shown through the patient's responses in a subjective refraction. Elimination of the subjective refraction is a very poor answer to the communication hardships presented by deaf and hearing-impaired individuals. PA1 c) Another solution used by examiners is to not use a refractor but to use a special glasses frame (known as a trial frame) that allows the insertion of loose trial lenses by hand. Since this special frame allows the free movement of the patient's head and the field of view is less restricted, the examiner can remain within the patient's view. However, this trial frame method is very time consuming. The frame must be continually removed from the patient's face and the loose lenses changed by hand. It is difficult to quickly present alternative choices. Special refractive procedures such as a Jackson crossed cylinder test become difficult and less accurate when using a trial frame versus a refractor. Using a trial frame is time-consuming, cumbersome, and less accurate. PA1 d) Lastly, a means of communicating to a hearing-impaired patient while using a refractor is through touch. The patient's knee or shoulder can be touched by the examiner to indicate different choices, or to indicate the need for a response. This method is unsatisfactory as it requires the examiner to come into physical contact with the patient. Many individuals feel uncomfortable with forced physical contact. To some extent, such touching undermines the dignity of the individual. It could even provide an opportunity for inappropriate touching of the patient by the examiner. Also, only a very limited amount of information can be transmitted through touch. While this means of communication can and does work, a superior method of visual communication is wanting. PA1 a) to provide a means for a vision testing examiner to communicate effectively to a deaf or hearingimpaired individual during testing using a refractor; PA1 b) to provide a means for communication to a deaf or severely-hearing impaired individual who may also be visually impaired and as such, unable to read printed messages that may be displayed at the usual vision test distance of twenty feet; PA1 c) to provide a means for communication to the hearing-impaired which allows subjective refraction to be conducted with a refractor such that the refraction is faster and more accurate for the patient; PA1 d) to provide a means of communication to the hearing-impaired patient which is precise and unambiguous during subjective refraction testing; PA1 e) to provide a means of communicating to a deaf or hearing impaired person while conducting any other vision tests using a refractor such as phoria or vergence muscle balance testing; PA1 f) to provide a means of communicating to a deaf or hearing impaired individual which maintains the focus of the examinee at the proper test distance without requiring change of focus to and from a signaling device. PA1 g) to provide a means of visually communicating to a deaf or hearing impaired individual while conducting a vision test in a darkened room; PA1 h) to provide a means of communication to the deaf or hearing-impaired which maintains their dignity as a person while testing their vision using a refractor; PA1 i) to provide a means of effectively communicating to the deaf and hearing-impaired during subjective refraction testing and other vision tests such that their most important sense of sight is maximized.